Took my car to my mechanic today to check out a grinding/clanging noise in the rear end. He told me that it's the differential and that it'd cost me around $400-$500 to replace everything in there. I'm positive he's not jerking me around on what needs to be done because I've been going to this guy for a while and he always triple checks to make sure he's not doing work and charging me for stuff I don't need. I just want to know if this is a good price. Thanks in advance guys.

 

Don't know if that's a good price in San Diego, but it's about half of what it would cost here in Hawaii.

 

Hmmm. You just had your tranny rebuilt, right?

Also, are you sure you have posi-additive in the diff? (Only applicable if you have a posi, which you should) If you don't the rear will make some funky noises as the clutches can't operate properly. More noticeable taking a turn, though. Is yours constant? Did he show you what was wrong? I like seeing what's broke when they tell me it's broke.

 

Yeah, the tranny was just rebuilt. As for posi-additive, I'm not sure. The "funky noises" sounds familiar though, and it IS more noticeable taking a turn. Also more noticeable when it's warm than when I first get going for the day. What kind of posi-additive should I get, and if there's already some in there (since I don't know), will it hurt to dump in a little more? One more question... is it hard to get at where to put the diff oil in when the car's on the ground? I live in an apartment complex and don't have a friend with a lift.

 

Disclaimer-type statement: I write small books for posts.

First off, do you have the little SPI sticker in your center console? It lists the RPO codes for pretty much everything the car came with, and would let you know your rear-end ratio, and if it was a posi unit or just an open differential. This is important. Plus, once you know what the car originally came with, you can figure out if it's been hacked up or anything by previous owners.

I'm guessing you have a ten-bolt 2.73 rear? The 9-bolt BW unit wasn't common until '87. You could take it to a quickie-lube place and have them change all the diff fluid out, but the one I went to didn't add the additive, and I needed it! You can buy the stuff in little tubes at Checker or wherever for less then ten bucks. Since I have nothing but 9-bolts, I'm not sure how to add it to a ten-bolt, as 9-bolts have a little rubber plug that you pull and it's pretty easy to add whatever if all you got is a rubber plug. Ten-bolts are different, but I've never really seen one up close before to give you the Gospel Truth about them.

Just like any recipie, you can have too much of a good thing. Ever tasted cookies with too much salt in the recipie? YUCK. However, if you add the additive and the clunking goes away, you only spent ten or so bucks on it, instead of finding out that you need new everything.

NOTE! This assumes you have a limited-slip diff. Open diffs... I don't have a clue. Not enough lubricant back there, maybe? Have you had the fluid changed at all? Might be a good idea, considering the rest of the car and the problems you've been having. One of the first things I did with my GTA was getting the diff fluid changed out. Might not have made it a tire-spinning moster, but it was a bit of piece of mind. I'll go find out and tell you what I find.

 

Darn it - I'll have to look it up in my manual, I can't find anything for that here, amazingly...

You're going to need a set of tools so you can remove the cover, to look at it yourself, if you go that route. Checker sells basic sets of tools for under sixty bucks, that or Wal-mart. If you have the cash for it, go pop for some Craftsman tools, you really get what you paid for them, and if htey break, you can take back the busted stuff for a free exchange, no questions asked.

 

braindedracefan, for some reason, I have not a lot of success getting expert advice about differentials in the Pacific Forum.

You might fare better than I, but it's doubtful...

Have you submitted your question in the TGO area where drivetrain experts hang out, like in the ...

TGO Transmissions and Drivetrain forum?

 

Well...if it really needs a full rebuild, retail prices on parts would be around $300 for new gears, bearings & seals. $200 for labor sounds about right...maybe could be a little low because (in my opinion) it's easier to pull the entire rear to shim the new gearset as opposed to doing it while attached to the car. If it is the gearset -- the price seems slightly low. If it's not the gearset...that price is a bit high.